Sewing machine, and computer-readable storage medium storing sewing machine control program

1. A sewing machine comprising:

an image pickup device that is disposed at a position where an image can be picked up over a sewing machine bed;

a feature point coordinates calculation device that extracts a plurality of feature points arranged over a range such that the image pickup device can pick up images therein from the image picked up by the image pickup device and that calculates two-dimensional coordinates of the extracted feature points;

a reference coordinates storage device that stores reference coordinates, which are previously measured three-dimensional coordinates of the feature points;

a correlation device that correlates the reference coordinates stored in the reference coordinates storage device with the feature point coordinates, which are the two-dimensional coordinates of the feature points calculated by the feature point coordinates calculation device; and

a parameter calculation device that calculates a parameter about the image pickup device based on a result of correlation by the correlation device.

2. The sewing machine according to claim 1 , wherein:

the feature point is at least one vertex of a square shaped hole and a center of a circular hole formed in a needle plate placed on the sewing machine bed.

3. The sewing machine according to claim 1 , wherein the feature point is a point provided on a surface of the needle plate.

4. The sewing machine according to claim 1 , further comprising:

an embroidery apparatus that moves an embroidery frame that holds a work cloth in a condition where the embroidery frame is placed on the sewing machine bed,

wherein the feature point is at least one of:

the point provided on the embroidery frame; and

the point provided on a template placed on the embroidery frame.

5. The sewing machine according to claim 1 , further comprising:

an embroidery apparatus that moves an embroidery frame that holds a work cloth in a condition where the embroidery frame is placed on the sewing machine bed, wherein:

at least one point is provided at least on the embroidery frame and on a template placed on the embroidery frame;

the reference coordinates storage device defines the point, as the feature point, in a condition where the embroidery frame is moved by the embroidery apparatus and disposed at a plurality of predetermined positions on the sewing machine bed and then stores the respective reference coordinates of the feature point at the predetermined positions; and

the feature point coordinates calculation device moves the embroidery frame to the plurality of predetermined positions by the embroidery apparatus, picks up an image over the sewing machine bed by the image pickup device, extracts the feature point, and calculates the two-dimensional coordinates of the feature point.

6. The sewing machine according to claim 1 , further comprising:

an image processing device that processes an image picked up by the image pickup device, in accordance with the parameter calculated by the parameter calculation device.

7. The sewing machine according to claim 1 , further comprising:

a three-dimensional coordinates calculation device that calculates the three-dimensional coordinates of a point in an image picked up by the image pickup device, in accordance with the parameter calculated by the parameter calculation device.

8. The sewing machine according to claim 1 , further comprising:

a two-dimensional coordinates calculation device that calculates the coordinates of a point in the two-dimensional coordinate system, which the coordinates of a predetermined point represented in three-dimensional coordinates are projected onto, in accordance with the parameter calculated by the parameter calculation device.

9. The sewing machine according to claim 1 , wherein the image pickup device is a CMOS image sensor.

10. A non-transitory computer-readable storage medium storing a control program executable on a sewing machine, the program comprising:

picking up an image over a predetermined range over a sewing machine bed;

extracting a plurality of feature points arranged in the predetermined range from the image picked up and calculating two-dimensional coordinates of the extracted feature points;

storing reference coordinates, which are previously measured three-dimensional coordinates of the feature points;

correlating the reference coordinates stored with the feature point coordinates, which are the two-dimensional coordinates of the feature points calculated; and

calculating a parameter about the image pickup based on a result of correlation.

11. The storage medium according to claim 10 , wherein:

the feature point is set to at least one point that is placed on at least one of the embroidery frame of the sewing machine in a condition where the embroidery frame is disposed at a predetermined position on the sewing machine bed and a template placed on the embroidery frame;

storing reference coordinates, the reference coordinates of the feature point are stored at each of a plurality of predetermined positions on the sewing machine bed disposed by permitting the embroidery frame to move; and

extracting a plurality of feature points, the embroidery frame is moved to the plurality of predetermined positions, an image is picked up over the sewing machine bed, the feature point is extracted, and the two-dimensional coordinates of the feature point are calculated.

12. The storage medium according to claim 10 , further comprising:

processing an image picked up, in accordance with the parameter calculated.

13. The storage medium according to claim 10 , further comprising:

calculating the three-dimensional coordinates of a point in an image picked up, in accordance with the parameter calculated.

14. The storage medium according to claim 10 , further comprising:

calculating the coordinates of a point in the two-dimensional coordinate system, in which the coordinates of a predetermined point represented in the three-dimensional coordinates are projected onto, in accordance with the parameter calculated.